Sliding Canopy Help on Spitfire
 

Hi Folks,

I am in the process of readying my Spitfire MK VIII for competiton this year and I am not staisfied with the current setup for the sliding canopy. Heres what I have right now...

The plastic canopy is glued to two music wires which are soldiered to brass cables which snake through the the brass channel and plastic rod down to a servo below the floor.

This allows me to open and close the canopy by remote (which is very cool) but the brass wire tends to stick and bind and I really and not satisfied with this setup.

I know you guys have great solutions for this situation and I patiently await your responses!


Thanks in advance,

Rick

sliding canopy
 

cub boy.. you might consider making your canopy manuel and get rid of the wires and cable.. makes things easier to manage at least.. BobH

Sliding Canopy Help on Spitfire
 

To make the sliding canopy manual is a retreat . We always have to challenge ourself and strive to reach higher levels in whatever we do, otherwise we will stuck in wherever we are. When I decided to do remote sliding canopy on my plane many including myself thought it can not be done or it is too complex etc. But I decided to do it and I did it and made it to work flawlessly, so go for it Rick and do not give up. My plane is FW190 so what I did may not apply to you but I will glad to share some of my ideas with you :D

sliding canopy
 

Foxx I appreciate your view point but if memory serves.. the full scale spit has a manuel canopy. So.. he would be authentic from that stand point. I dont think its too much of a challange for the spitfire to have it operated via an air valve.
Cub-boy.. mount an air valve in the aft portion of the fuse.. behind the canopy.. attach the push/pull rods to the canopy sliders, both sides. Just keep them inline so they dont bind.. putting sliders at the front and rear of the sliding canopy will help keep it from twisting.. you will have a 4 point attachment (2 per side). That may be close to what you already have?.. Regards BobH.

Sliding Canopy Help on Spitfire
 

Bob full scale spit also has full scale pilot to close/open the canopy . :D
I thought what you meant by manual was rubber band etc. but now I realize what you were refering to by saying making it manual .your suggestion should be a great help to Rick.

sliding canopy..
 

Foxx, Thanks, I hope it helps him.. I debated putting a sliding canopy that was linked with my gear so when the gear retracted the canopy closed etc. I still can do that but I probably won't have it slide via an air valve. I built an interior for the plane which looks pretty good, hopefully... but its more plumbing that I want to do behind the cockpit. My plane is a Yellow P-47 with a glass fuse and not a lot of access behind the servos. I think I'll end up opening the canopy by hand when no one is looking LOL!!... BobH.

Sliding Canopy Help on Spitfire
 

Hi Guys,

I appreciate all of your responses and your suggestions. I am determined to resolve this problem so the canopy can open and close by remote control.

This function is part of my scale realism so I would like to keep it intact. I will keep reading your ideas and will post the final solution once I have developed one :-)


So keep adding to the ideas guys!

Rick,

Sliding Canopy Help on Spitfire
 

Bob I really like you idea to link the air cylinder to the landing gear, it should work great. Can you install the air cylinder under the canopy to work a slider instead of behind it ?. I never built a P47 therefore I really don,t know what I am talking about here. My canopy is servo operated via one of the auxiliary channels, but if I do it again I would definitely consider an air cylinder, since it is much more simpler system. I could only stuff a very small air tank in my plane which is only good for two gear rotation, putting additional cylinder was not really very practical, but on a 1/4 scale there is plenty of room to play around.

Sliding Canopy Help on Spitfire
 

Rick,
Back to your question on the binding of your canopy, have you tried lubricating the brass cables to help them slide better? also, is the reason it is binding is that it is trying to twist and push one side faster than the other? If this is the case you may need to stiffen the canopy frame itself. Some time back on RCU I saw pictures of a chap that was doing something as you describe but instead of having the cylinder behind the cockpit, he had it up front behind the dash. Seemed like a good place to put it as it was easy to get at with the wing off. Also I thought the 'pulling' action of the canopy to close it in the wind after take off would make more sense than fighting to 'push' it. Just a thought. There are a number of good threads on here if you do a seach.

Sliding Canopy Help on Spitfire
 

I have a solution that you should consider. Think of the flap mechinism on a Ziroli T-6. Got it? Good.

Rear of the cockpit, build a tube-in-bearing rod running horizontally across the fuse approximately the width of the canopy. (think torque tube) It could be a tube in a close fitting tube or you could make the bearings out of 1/8th plywood. Wood is best due to metal to metal contact issues. You can make 2, 3 or 4 bearings. The bearings are nothing more than 1/8th ply cut to mount the torque tube in place with a hole in it. Tight enough to reduce slop, loose enough that the tube rotates freely. More bearings reduce friction, to a point. Again, think of the flap activation mechinism in a T-6.

Centered on this rotating tube (torque tube) is your control arm. This will be connected by a short length of rod to your servo arm. The servo can be mounted anywhere. Front, under, behind the horizontal rod (torque tube) you just built.

Now, on the outer ends of your torque tube is one control horn at each end. This can be a soldered brass piece fitted over each end using a hole drilled in it and soldered/brazed into place. Or, it could be a nose wheel control arm with a set screw to hold it in position. If using the later be careful. Replace the set screw with a long bolt and have it go through the tube with a drilled hole, The usual set screw will bend the tube and not hold well.

From here it is a matter of building a control attach point on your canopy. A tab on either side of the canopy will attach by a servo rod to the control horns on the outside ends of your torque tube. Instead of activating flaps, you are now moving your canopy.

Sliding Canopy Help on Spitfire
 

Cub Boy. The problem I have had with sliding canopy's is that they tend to twist in the slide plane. It has been necessary to stiffen up the canopy so that both sides slide equally. I fear that an air cylinder will operate too quickly, and perhaps with too much force.

Les

sliding canopy.
 

Foxx. I suppose you could put the air cylinder some place other than behind the canopy maybe infront as some one suggested. I should consider that myself. Its been my experience with regards to sliding canopies that simple is good.. simpler is gooder..lol..
With my P-47 the canopy frame is Fiber glass wish is stiffer than just a canopy with the frame molded in. And it has a 3 point attachment.... two on the sides and one in the rear.. per the full scale. Most things that get out of alignment do so because of unequal force on one or more members with a limited bearing surface. A way to reduce that is to spread the load over a greater bearing surface.. which is why I suggested attaching the canopy at two points per side instead of one.
Lubrications have their place to help ease things along but they won't make up for misaligned parts very well. Effectively the problem returns after a while so the best thing is to design it such that the moving parts are normal to the plane to start with.. (thats plane as in plane geometry not as in airplane lol).
Les.. you can restrict the speed of air cylinders via several methods. The simplest being a wheel collar and a set screw. Tighten the set screw to restrict the diameter of the air line to your desired speed.
Regards BobH.

Sliding Canopy Help on Spitfire
 

Been there, done that Bob. Never could get things as slow as I have wanted. Even with Robard restrictors, and wheel collars. The wheel collar had a tendency to fatigue the tubing and cause leaks.

Les

sliding canopy
 

Les. I know what you mean.. I have used the UP1 and UP2 valve with great success.. you restrict the air flow via the valve. I haven't used the Robart valves so I can't speak for them..?? I have used the restrictors... mine are so old tho I don't know where I got them?..
My advice would make it a "hand job".. manual operation...LOL.....Regards BobH.

Sliding Canopy Help on Spitfire
 

Hi Guys,

You all bring up great points, I working on other areas of the plane while I await and read your responses!

Thanks to all who have provided their input and expereince thus far!!!


Rick,

RE: Sliding Canopy Help on Spitfire
 

Hi all,

I'm currently working on my Top Flite T34 and have just finished the bottom half of the fuselage. I plan to install a sliding canopy. Any idea on where I can get ready made rails or how I can make them? I plan to attach 4 robart air cylinders(2 for the front and 2 for the rear end) to operate the sliding mechanism.

Would appreciate if you a few of you can give me some advice.

Thanks

AS